1. Field of the Invention
The present invention relates to a fluorescence observation device for observing a subject using fluorescence, an endoscopic system, a processor device, and an operation method.
2. Description of the Related Art
In the medical field, a fluorescence observation device that includes an excitation light source that irradiates a subject with excitation light for emitting fluorescence by exciting an auto-fluorescent material contained in the subject or a fluorescent agent administered to the subject, an image sensor that images the subject with the fluorescence emitted from the auto-fluorescent material or the fluorescent agent, and an image processing device that generates a fluorescent image, which reflects the intensity distribution of the fluorescence emitted from the subject, based on an image signal by the fluorescence output from the image sensor (hereinafter, referred to as a fluorescent image signal) is known. Since the intensity of the fluorescence emitted from the auto-fluorescent material or the fluorescent agent is closely related to the medical condition of the subject, the therapeutic effect of drugs, and the like, the fluorescence observation device is used for, for example, pathological diagnosis or drug development. In addition, in order to perform real-time diagnosis based on a fluorescent image, an endoscopic system configured to include a light source device, an endoscope, a processor device, and the like may have the configuration of the fluorescence observation device (WO2011/099425A and WO2013/035450A).
In recent years, diagnosis using the oxygen saturation of blood hemoglobin has been performed. The oxygen saturation of blood hemoglobin is calculated based on the reflection intensity, for example, by irradiating the subject with light (hereinafter, referred to as signal light) in a wavelength band where the absorption coefficients of oxygenated hemoglobin and reduced hemoglobin are different (JP2012-213550A).